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Ecology, 87(4), 2006, pp. 931941 2006 by the Ecological Society of America
 

Summary: Ecology, 87(4), 2006, pp. 931941
2006 by the Ecological Society of America
SCALE DEPENDENCE OF REPRODUCTIVE FAILURE
IN FRAGMENTED ECHINACEA POPULATIONS
STUART WAGENIUS
1
Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota 55108-6097 USA and
Institute for Plant Conservation Biology, Chicago Botanic Garden, 1000 Lake Cook Road, Glencoe, Illinois 60022 USA
Abstract. I investigated reproduction in a three-year study of Echinacea angustifolia,
purple coneflower, growing in a fragmented prairie landscape. I quantified the local
abundance of flowering conspecifics at individual-based spatial scales and at a population-
based spatial scale. Regression analyses revealed that pollen limitation increased while seed set
and fecundity decreased with isolation of individual plants. Isolation, defined as the distance
to the kth nearest flowering conspecific, was a good predictor of pollen limitation, for all
nearest neighbors considered (k 133), but the strength of the relationship, as quantified by
R2
, peaked at intermediate scales (k 218). The relationship of isolation to seed set and
fecundity was similarly strongest at intermediate scales (k 34). The scale dependence of
individual density effects on reproduction (density of flowering plants within x meters)
resembled that of isolation. Analyses at a population-based scale showed that pollen limitation

  

Source: Ault, James R. - Chicago Botanic Garden

 

Collections: Biology and Medicine